Regarding the weight of arrangers, I used to carry heavy gear around 30 years ago, because there weren't any options. Today there are, and today I'm 30 years older, and today I'm moving my equipment 3-6 times a week.
The arthritis in my right wrist won't let me play weighted keys, even if I preferred to (but I don't). Weighted keys make it more difficult to emulate instruments.
I don't think of today's arrangers as flimsy and I don't recall having any problems with any of them, except the Roland G800. And btw it was pretty heavy. If you take a PSR3000 and beat on it like you would a Grand Piano, yes you will tear it up, but that's not what they are designed to do.
It's pretty easy to scoff at us old-timers who don't want to lift heavy gear. Trust me, we get there far sooner than you would ever believe.
If it weren't for arrangers, I would be probably be sitting in some office all day, counting the hours til I could get off work and rush home to spend a few hours playing music in my spare time.
I DEARLY love the Roland G70, but had to pass on it, after borrowing one for several months, because of the weight. As much as I love the sounds, styles and most features, it's too big a compromise. Jury is still out on the Korg PA800, but at least the weight is right.
Regarding arranger modules, I had great success using the Ketron Midjay with a light-weight controller. There were a few compromises with control, but really not many. Sometimes I wonder why I got away from that. If the PA800 doesn't work out, I will probably go back to it, and then eagerly look forward to the next whatever.
DonM